Magnitude function

magnitude.raku

#| Calculates the position of the first digit.  Only accepts values ≥ 0
sub magnitude($no is raw) {
    # Special case 0 to avoid infinite loop
    return 1 if $no == 0;
    
    # Need a copy, because binding is slightly faster faster, `is copy` complains about LHA
    my $n := $no;
    
    my $result := 1;

    # If less than 1, our result will be negative.  Get $n to be positive first
    while $n < 1     { $result := $result - 8; $n    := $n    * 10000_0000 }
    
    # Int math is MUCH faster, ditto for multiplication.
    $n := $n.Int; my $comp := 1;
    
    # Bump up the result and comparison values.  These can be different, but
    # 8/4/1 seems to be a nice happy balance of speed/complexity.
    while $n > $comp { $result := $result + 8; $comp := $comp * 10000_0000 }
    while $n > $comp { $result := $result + 4; $comp := $comp * 10000      }
    while $n > $comp { $result := $result + 1; $comp := $comp * 10         }
    
    # The position of the first digit
    return $result;
}